1. Field of the Invention
The present invention relates to a ceramic composition containing a polyacetal binder. The composition is particularly suitable for injection molding. The present invention also relates to a process of molding using the described ceramic composition.
2. Description of the Prior Art
It is known in the art that moldable ceramic compositions may be formed by combining ceramic powders with various binding agents. For example, U.S. Pat. No. 4,071,594 discloses an extrudable ceramic composition comprising ceramic particles and a binding agent. The binding agent is a high molecular weight (at least 400,000) linear chain polyethylene oxide polymer with an organic solvent such a trichloroethylene or ethylene dichloride.
U.S. Pat. Nos. 4,301,020 and 4,267,065 describe ceramic compositions incorporating a dispersant to improve the rheological properties of a ceramic slurry. The dispersant comprises ammonium citrate and polyethylenimine.
U.S. Pat. No. 4,180,538 discloses a ceramic composition suitable for extrusion comprising an inorganic raw material powder and a plasticizer which is either a mono-liquid type resin, such as polyvinyl butyral resin, or a hydraulic setting resin mainly consisting of a polyurethane isocyanate prepolymer.
U.S. Pat. No. 3,309,212 relates to a ceramic slurry suitable for molding comprising ceramic particles distributed in a liquid binder such as ethyl silicate.
U.S. Pat. No. 3,496,256 describes a composition for molding refractory bodies comprising refractory particles admixed with a binding agent. The refractory particles may be metal oxides such as alumina, zirconia or magnesia. The binding agent is prepolymerized furfuryl alcohol.
Despite the disclosure of various materials employed as a binding agent for ceramic compositions, no known prior art discloses the binding agent of the present invention which enables readily moldable ceramic composition to be formed and which vaporizes from a molded composition upon subsequent heating without resulting in any defects or weak spots in the molded article.